This disclosure relates generally to a turbomachine shroud, and more particularly, to a roughed inner surface of a turbomachine shroud.
As is known in the art, turbomachines extract energy from a flow of fluid. During operation, air is pulled into the turbomachine. The air is then compressed and combusted. The products of combustion expand to rotatably drive a turbine section of the turbomachine. As is known, shrouds (or outer seals) seal against rotating components (such as blades) of the turbomachine. Sealing interfaces between the rotating components and the shrouds increases engine efficiency. Current shroud designs utilize smooth inner shroud surfaces that are typically finished by diamond grinding.
Due to the shroud seal structure, the rotating components can come into contact with the inner surface of the shroud causing a “rub event”. When a rub event occurs, a portion of the rotating component may rub off and can smear on or otherwise get affixed to the inner surface of the shroud. Rubbing can result in undesirable thermal conditions and a decrease in the efficiency of the turbomachine. Current designs incorporate a “no-rub” clearance zone to prevent rub events from occurring and thereby minimize thermal events. The no-rub clearance zone is an clearance, or gap, between the rotating component and the shroud assembly. No-rub clearance zones, however, reduce the effectiveness of the seal.